Opacity Mask - how do I get access to other layers?

Hi, I'm in Illustrator, CC, on a Mac - is that is imporatant....

I am trying to learn opacity masks, and I figured out how to make one.  Yippee.

But now that I have a opacity mask, my layers panel only show that opacity layer.  How to I get back to my normal layers panel, and edit other stuff?

It shouldn't be that hard, right?

TIA